Castanet

60-YEARS-in-Ktown wrote: Steel is a poor brake drum material, cast iron has a better coefficent of friction I think ...at any rate usually cast iron.
And I am thinking nodular iron maybe. This you could tell if they were being turned, they would try to form curled chips, which may crumble if you hit them. Regular cast iron, the material comes off in a powdery form.
When the drums over heated, are the studs turning straw color or brown or blue. ..? If they are not changing color it did not affect the heat treatment. You mention tempering... tempering is a process done AFTER Heat Treating. Heat Treating makes it hard and brittle, tempering after that reduces hardness and increases toughness.

Yes, cast iron is self lubricating, and has good wear properties under sliding conditions. Grey cast iron is the better choice because of the greater ability to absorb vibrations. Ductile iron has higher strength, but that is not needed for a brake drum.

The trailer fire was the result of a slow air leak and the trailer losing its air causing the brakes to slowly come on.

A slow air leak in the trailer does not cause the brakes to slowly come on. You can drive forever with a slow leak.

Truck has 120 psi max air pressure available. The compressor will keep up to a small leak. All that happens is that the compressor will kick in more often as the pressure drops to 90 psi. The compressor will shut off when it reaches 120 psi.

A trailer supply line rupture will cause the trailer supply to exhaust and tractor protection valve to close. The trailer spring brakes will apply ( all trailer wheels ).

An air leak would not cause a fire. An empty truck and trailer combination will rarely have to use the brakes, A very possible cause is a brake shoe failure causing that one drum to heat up and cause a fire.

Class 1 driver since 1981.

more likely would be a wheel seal failure the oil leaks out bearings get hot and start to seize on the spindle and poof you have fire

Had that happen LTD. Bearing seizes up ( still had oil this time ). Tire locks up = smoke from skidding tire. Should notice that before a fire starts.

I have the safety memo from DCT stating that it was an air leak.

Ive experienced this twice myself with a super b logging trailer coming out of the bush with a load of logs on. I was lucky enough to catch it before my brakes got hot enough to catch on fire but they were smoking.

The first time a piece of wood had come down and hit the lever closed that supplied air to the pup.

The second time I had an air bag go. Yes I was losing air at the truck but the compressor was keeping, However the air loss at the pup was enough to slowly apply the brakes. I couldnt see the smoke because of the dust.I knew there was a problem because I had to drop a gear to come up a hill I should have came up with no problems.

tootall23 wrote:A slow air leak in the trailer does not cause the brakes to slowly come on. You can drive forever with a slow leak.

Truck has 120 psi max air pressure available. The compressor will keep up to a small leak. All that happens is that the compressor will kick in more often as the pressure drops to 90 psi. The compressor will shut off when it reaches 120 psi.

A trailer supply line rupture will cause the trailer supply to exhaust and tractor protection valve to close. The trailer spring brakes will apply ( all trailer wheels ).

An air leak would not cause a fire. An empty truck and trailer combination will rarely have to use the brakes, A very possible cause is a brake shoe failure causing that one drum to heat up and cause a fire.

Class 1 driver since 1981.

Do brakes on a trailer come on if theres no air in system?

A rupture is a little different than a slow air leak true or false?

If there is an air leak at the pup of the trailer and it was slowly losing air pressure would the brakes not slowly come on?

1) Yes, it takes full air to take brakes off.
2) Rupture or leak, when the compressor can no longer maintain and loses ground,
The spring side of the system goes full application.
It happens quickly,

7 minutes, well described.
https://www.bing.com/videos/search?q=br ... ORM=VDRVRV

Lol at some of the theories on here. It's fun being a mechanic some days and some days not.

jsytnick wrote:Lol at some of the theories on here. It's fun being a mechanic some days and some days not.

Why not gracefully answer and educate then ?

Or,

education on such things hold no value ?

dirtybiker wrote:

jsytnick wrote:Lol at some of the theories on here. It's fun being a mechanic some days and some days not.

Why not gracefully answer and educate then ?

Or,

education on such things hold no value ?

Why bother, sounds like everyone on here knows everything already. I've been arguing for 20 years in shops with people that think they know everything, I'm not about to continue that online. Just stating an observation is all.

Edit-Went through the thread and found 12 pieces of misinformation, you can tell the guys that are actually involved in trucking vs the peanut gallery on the side.

Fair enough....

Thanks,

People are a pain, thanks for keeping us safe....er....

dirtybiker wrote:Fair enough....

Thanks,

People are a pain, thanks for keeping us safe....er....

I've bounced around lately from oilfield fleet to retail to hybrid back to fleet. Fleet is great, PM programs in place are a great thing. It's honestly scary seeing what's out there on the roads and there's not enough CVSE enforcement to catch it all.

jsytnick wrote:
Why bother, sounds like everyone on here knows everything already. I've been arguing for 20 years in shops with people that think they know everything, I'm not about to continue that online. Just stating an observation is all.

Edit-Went through the thread and found 12 pieces of misinformation, you can tell the guys that are actually involved in trucking vs the peanut gallery on the side.

You seem just like the people you are complaining about.

jsytnick wrote:

Why bother, sounds like everyone on here knows everything already. I've been arguing for 20 years in shops with people that think they know everything, I'm not about to continue that online. Just stating an observation is all.

You sound like a lot of the mechanics I've dealt with